Methods and apparatus for multiple temperature levels

ABSTRACT

Methods and apparatus for thermal management according to various aspects of the present invention comprise a heat exchanger and one or more controllable thermal transfer elements. In one embodiment, the thermal transfer elements comprise thermoelectric coolers. The thermal transfer elements are thermally coupled to the heat exchanger. Components on a surface near the thermal transfer elements may be selectively cooled by controlling the thermal transfer elements.

BACKGROUND OF THE INVENTION

Electrical component manufacturers strive to shrink their designs and pack more technology into a compact footprint. Advances in materials and fabrication processes have lead to much progress in this area. Compact designs, however, have led to many thermal energy producing elements packed into a tight space. Heat can be an enemy of electrical components and can decrease efficiency and reliability.

A heat sink absorbs and dissipates heat using thermal contact. Heat sinks are widely used in electronics, and have become almost essential to modern central processing units. In common use, a heat sink is a metal object brought into contact with an electronic component's hot surface. Microprocessors and power handling semiconductors are examples of electronics that use a heat sink to reduce their temperature through increased thermal mass and heat dissipation.

Cold plates may also be used as heat sinks. In a world of compact designs with increasing power densities, cold plates are satisfying demanding contact cooling requirements in applications as diverse as high-powered electronics, lasers, power generation, medical equipment, and military and aerospace. For high watt densities, when air-cooled heat sinks are inadequate, liquid-cooled cold plates are the ideal high-performance heat transfer solution. Generally, a liquid-cooled cold plate is a channel imbedded in a low thermal resistive solid surface that uses a fluid to dissipate heat. While effective, cold plates provide a single level of cooling. Different components requiring different temperatures require separate heat sinks and/or cold plates.

SUMMARY OF THE INVENTION

Methods and apparatus for thermal management according to various aspects of the present invention comprise a heat exchanger and one or more controllable thermal transfer elements. In one embodiment, the thermal transfer elements comprise thermoelectric coolers. The thermal transfer elements are thermally coupled to the heat exchanger. Components on a surface near the thermal transfer elements may be selectively cooled by controlling the thermal transfer elements.

BRIEF DESCRIPTION OF THE DRAWINGS

Representative elements, operational features, applications and/or advantages of the present invention reside in the details of construction and operation as more fully depicted, described or otherwise identified—reference being made to the accompanying drawings, images, figures, etc. forming a part hereof, wherein like numerals refer to like parts throughout. Other elements, operational features, applications and/or advantages will become apparent in view of certain exemplary embodiments recited in the disclosure herein.

FIG. 1 is a cross section of a cooling system according to various aspects of the present invention; and

FIG. 2 is a cross section of a cooling system having two sets of thermal transfer elements.

Elements in the figures, drawings, images, etc. are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present invention.

Furthermore, the terms ‘first’, ‘second’, and the like herein, if any, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. Moreover, the terms ‘front’, ‘back’, ‘top’, ‘bottom’, ‘over’, ‘under’, and the like in the disclosure and/or in the claims, if any, are generally employed for descriptive purposes and not necessarily for comprehensively describing exclusive relative position. Any of the preceding terms so used may be interchanged under appropriate circumstances such that various embodiments of the invention described herein, for example, are capable of operation in other configurations and/or orientations than those explicitly illustrated or otherwise described.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The descriptions are of exemplary embodiments of the invention and the inventors' conception of the best mode and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description is intended to provide convenient illustrations for implementing various embodiments of the invention. Changes may be made in the function and/or arrangement of any of the elements described in the disclosed exemplary embodiments without departing from the spirit and scope of the invention.

Various representative implementations of the present invention may be applied to any system for thermal energy transfer. The present invention may be described in terms of conventional plates, heat transfer media, and fluids. Plates in accordance with the present invention may comprise any number of conventional materials including, but not limited to, ceramics, metals, plastics, fiberglass, glass, various other inorganic and organic materials and/or the like. Furthermore, such plates may comprise various forms, layers, walls, sizes, thicknesses, textures and dimensions and/or the like.

Heat transfer media in accordance with various aspects of the present invention may comprise any suitable materials and/or systems for heat transfer. In one embodiment, heat transfer media may comprise finstock. In another embodiment, heat transfer media may comprise various thermocouples, sensors and/or the like. In yet another embodiment, heat transfer media may comprise heat sinks, cold plates and/or the like.

Referring to FIG. 1, a cooling system 100 according to various aspects of the present invention exhibiting multiple temperature levels at different locations comprises a heat exchanger and one or more thermal transfer elements. In the present embodiment, the heat exchanger is defined by first and second thermal transfer layers 110, 120 defining a cooling fluid channel 140, through which a heat transfer medium 145 may flow. One or more thermal transfer elements 160 may be disposed between and thermally coupled to the second and third thermal transfer layers 120, 130. Elements to be cooled 170, 171, 172, 173 may be thermally coupled to the first and third thermal transfer layers 110, 130. By controlling the flow of heat transfer medium 145 through the cooling fluid channel 140 and/or the thermal transfer elements 160, the temperatures of the elements to be cooled 170, 171, 172, 173 may be individually controlled.

The thermal transfer layers 110, 120, 130 facilitate heat transfer through the layers 110, 120, 130. The thermal transfer layers 110, 120, 130 may comprise any suitable material exhibiting low resistance to thermal energy transfer. For example, the thermal transfer layers 110, 120, 130 may comprise conventional finstock material, for example comprising a copper or aluminum alloy. The thermal transfer layers 110, 120, 130 may comprise the same material or different materials, and each thermal transfer layer 110, 120, 130 may comprise one or more materials.

In the present embodiment, the thermal transfer layers 110, 120, 130 comprise substantially flat elements comprising highly thermally conductive materials. The thermal transfer layers 110, 120, 130 are disposed substantially parallel to one another and separated by a selected gap. The gap between the first and second thermal transfer layers 110, 120 defines the cooling fluid channel 140, which may be further defined in any suitable manner, such as with additional walls, inlets and outlets, baffles, interior walls, and the like. The thermal transfer elements 160 are disposed within the gap between the second and third thermal transfer layers 120, 130.

The first and third thermal transfer layers 110, 130 also include external surfaces upon which the elements to be cooled 170, 171, 172, 173 are thermally coupled. In the present embodiment, the external surfaces are substantially flat or otherwise configured to accommodate the elements to be cooled 170, 171, 172, 173.

The cooling fluid channel 140 conducts the heat transfer medium 145 between the first and second thermal transfer layers 110, 120. The heat transfer medium 145 flowing through the cooling fluid channel 140 transfers heat away from the first and second thermal transfer layers 110, 120. The cooling fluid channel 140 may be configured in any appropriate manner to facilitate the flow of the heat transfer medium 145, for example including interior walls to define one or more straight or a serpentine channels between an inlet and an outlet of the cooling fluid channel 140. The dimensions of the cooling fluid channel 140 may be selected according to any appropriate criteria, such as to accommodate selected amounts of heat transfer medium 145, flow rates, and the like.

The heat transfer medium 145 may comprise any material for removing the thermal energy from the thermal transfer layers 110, 120. The heat transfer medium 145 may comprise any fluid, liquid/vapor or liquid/gas mixture suitable for cooling, stabilizing temperature, and/or the like. In the present embodiment, the heat transfer medium 145 may comprise a coolant 142. In another embodiment, in warming applications, the heat transfer medium 145 may be adapted to transfer heat to the exterior of the system via the thermal transfer layers 110, 120, 130. In one exemplary embodiment, the coolant 142 comprises air. Alternatively, the coolant 142 may comprise another appropriate coolant, such as water, an ethylene glycol/water mixture, de-ionized water, oil, dielectric fluids, polyalphaolefin and/or the like.

The thermal transfer elements 160 transfer heat to or from one thermal transfer layer 110, 120, 130. For example, the thermal transfer elements 160 may transfer heat from the third thermal transfer layer 130 to the second thermal transfer layer 120. The thermal transfer elements 160 may comprise any suitable passive or active systems for controlling the flow of thermal energy. For example, the thermal transfer elements 160 may comprise conventional heat pump technologies for actively and controllably transferring heat. The thermal transfer element 160 may be a smart cooling channel or it may be an electronically controlled selectable device for controlling absorption of thermal energy. In one embodiment, thermal transfer elements may comprise elements having a size of approximately 1.25 inches squared, and an approximately ⅛ inch thickness.

In the present embodiment, the thermal transfer elements 160 include at least one thermoelectric cooler (TEC) 165. TECs 165 may range in size and/or shape. For example, in one embodiment, TECs comprise one or more pellets of approximately 1/50,000 inch squared in size and 1/80,000 inch in length. TECs 165 utilize the Peltier eftect, which occurs when current passes through two dissimilar metals or semiconductors, such as n-type and p-type materials, that are connected to each other at two junctions. The current drives a transfer of heat from one junction to the other such that one junction cools while the other heats.

The thermal transfer element 160 may be configured to transfer heat to or from a selected portion of, or the entirety of, one or more of the thermal transfer layers 110, 120, 130. For example, one or more thermal transfer elements 160 may be thermally coupled to the third thermal transfer layer 130 opposite one or more elements to be cooled 172, 173. The thermal transfer elements 160 may also be coupled to the second thermal transfer layer 120 to facilitate the transfer of heat between the second and third thermal transfer layers 120, 130. In the present embodiment, the second thermal transfer layer 120 is coupled to the fluid cooling channel 140. The thermal transfer element 160 may transfer heat from the third thermal layer 130 to the second thermal transfer layer 120, and the coolant 142 cools the second thermal transfer layer 120 to remove the heat.

Any appropriate number and arrangement of thermal transfer elements 160 may be employed, for example to control the temperature of different areas and/or to different degrees. For example, referring to FIG. 2, the cooling system 100 may further comprise a fourth thermal transfer layer 240 parallel to and proximate the first thermal transfer layer 110. One or more thermal transfer elements 160, such as TECs 165, may be disposed between and thermally coupled to the first and fourth thermal transfer layers 110, 240. Addition layers of thermal transfer layers 110, 120, 130, cooling channels 140, and thermal transfer elements 160 may be shaped, added, and arranged according to the needs of various applications and environments.

The thermal transfer elements 160 may be configured to be actively controllable, for example to control whether and/or at what rate heat is transferred by the thermal transfer elements 160. For example, the TECs 165 of the present embodiment may be controlled by adjusting the current provided to the various TECs 165. The thermal transfer elements 160 may be controlled, however, in any appropriate manner. In addition, the thermal transfer elements 160 may be independently controllable. For example, the TECs 165 may be addressable or otherwise selectable to individually control the TECs 165 or groups of TECs 165. Consequently, areas of the cooling system 100 associated with different elements to be cooled 170, 171, 172, 173 may be separately and independently regulated.

The thermal transfer elements 160 may be controlled in any appropriate manner by any suitable mechanism. For example, the cooling system 100 may further include a control system and one or more sensors connected to the control system and in thermal contact with various portions of the cooling system 100. The control system may control the various elements of the cooling system 100 to maintain selected temperatures or ranges of temperatures in selected areas, for example by controlling the current supplied to the various TECs 165 and/or the flow of heat transfer medium 145 through the cooling fluid channel 140.

The elements to be cooled 170, 171, 172, 173 may comprise any appropriate systems items, or devices to be subjected to temperature regulation. In one embodiment, the elements to be cooled 170, 171, 172, 173 comprise electronic components, such as integrated circuits. The elements to be cooled 170, 171, 172, 173 may be coupled to the thermal transfer layers 110, 120, 130, 240, for example via a thermal coupling to transfer heat from the elements to be cooled 170, 171, 172, 173 to the thermal transfer layers 110, 120, 130, 240.

In the present embodiment, the electronic components include a substantially flat surface abutting the substantially flat outer surfaces of the thermal transfer layers 110, 120, 240. The electronic components may be coupled to the thermal transfer layers with any appropriate materials, such as a thermally conductive grease or other thermally conductive pads disposed between the electronic components and the thermal transfer layers 110, 120, 240 to ensure optimal thermal contact. Thermally conductive greases may comprise any appropriate materials, such as beryllium oxide, aluminum nitride, or finely divided metal particles, like colloidal silver. Thermally conductive pads may comprise any suitable pads, such as CHO-THERM® Insulator Pads by Chomerics, a division of Parker Hannifin Corporation (Woburn, Mass.).

Further, a clamping mechanism, a screw, or a thermal adhesive may hold the electronic component on the corresponding thermal transfer layers 110, 120, 240. The clamping mechanism and screws may comprise any low thermal conductive materials, such as stainless steel. In one embodiment, adhesives, clamping mechanisms and/or screws are only placed on one side of the TECs to allow for thermal expansion. For example, a TEC may expand at a different rate, temperature and/or time than another TEC. Referring to FIG. 2, by fastening a TEC on only one side, the TEC is allow to expand and/or slide lengthwise, such as in the direction of flow of the fluid channel 140. If TECs are fastened on two sides, shearing may occur. In embodiments where TECs are wired in series, this could cause a disruption and/or a shut down in energy transfer.

In one embodiment, the cooling system 100 may provide different temperatures for different spatial areas of the cooling system 100. For example, heat may be removed from one side of the cooling system 100 or area of a thermal transfer layer 110, 120, 240 to achieve one or more temperature levels, while heat may be removed from a second side of the cooling system 100 or area of a thermal transfer layer 110, 120, 240 to provide a different temperature level or levels.

For example, referring to FIGS. 1 and 2, the elements to be cooled 170, 171, 172, 173 may begin generating heat, such as by activating the electronic components. The heat transfer medium 145 flows through the cooling channel 140. As the elements to be cooled 170, 171, 172, 173 generate heat, the heat is transferred to the thermal transfer layer 110, 120, 240 to which element is attached.

The heat is transferred from the thermal transfer layers 110, 120, 240 to the heat transfer medium 145. The heat may be transferred substantially directly to the heat transfer medium 145, for example via direct contact between the heat transfer medium 145 and the thermal transfer layer 110. Alternatively, the heat may be transferred indirectly, for example across two thermal transfer layers 120, 130 and one or more thermal transfer elements 160. More particularly, the heat may transfer from the elements to be cooled 172, 173 to the third thermal transfer layer 130. The third thermal layer 130 may be selectively cooled by the thermal transfer elements 160, which transfer heat from the third thermal layer 130 to the second thermal layer 120. The heat from the second thermal layer 120 is transferred away from the cooling system 100 via transfer from the second thermal layer 120 to the heat transfer medium 145.

In the present embodiment, the temperature of the elements to be cooled 172, 173 may be actively controlled by monitoring the temperatures of the elements to be cooled 172, 173 and/or the nearby areas and adjusting the thermal transfer elements 160 accordingly. For example, the temperature may be sensed by the sensors near or on the various elements to be cooled 172, 173 and provide to the control system. The control system may compare the measured temperature to a target temperature and adjusts the thermal transfer elements 160 to maintain desired temperatures. Separate sensors and thermal transfer elements 160 facilitate independent temperature control for the various elements to be cooled 172, 173.

The particular implementations shown and described are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of the present invention in any way. Indeed, for the sake of brevity, cold plates, heat transfer media, fluids and/or the like may not be described in detail herein.

In the foregoing specification, the invention has been described with reference to specific exemplary embodiments. Various modifications and changes, however, may be made without departing from the scope of the present invention as set forth in the claims. The specification and figures are to be regarded in an illustrative manner, rather than a restrictive one and all such modifications are intended to be included within the scope of the present invention. Accordingly, the scope of the invention should be determined by the claims and their legal equivalents. For example, the steps recited in any method or process embodiments may be executed in any order and are not limited to the specific order presented in the claims. Additionally, the components and/or elements recited in any apparatus embodiment may be assembled or otherwise operationally configured in a variety of permutations to produce substantially the same result as the present invention and are accordingly not limited to the specific configuration recited in the claims.

Benefits, other advantages and solutions to problems have been described above with regard to particular embodiments; however, any benefit, advantage, solution to problems or any element that may cause any particular benefit, advantage or solution to occur or to become more pronounced are not to be construed as critical, required or essential features or components of any or all the claims.

As used herein, the terms “comprising”, “having”, “including”, or any contextual variant thereof, are intended to reference a non-exclusive inclusion, such that a process, method, article, composition or apparatus that comprises a list of elements does not include only those elements recited, but may also include other elements not expressly listed or inherent to such process, method, article, composition or apparatus. Other combinations and/or modifications of the above-described structures, arrangements, applications, proportions, elements, materials or components used in the practice of the present invention, in addition to those not specifically recited, may be varied or otherwise particularly adapted by those skilled in the art to specific environments, manufacturing specifications, design parameters or other operating requirements without departing from the general principles of the same. 

1. A thermal management system, comprising: a heat exchanger, comprising a first thermal transfer layer; a second thermal transfer layer proximate the first thermal transfer layer; and a thermal transfer element thermally coupled to the first thermal transfer layer and the second thermal transfer layer.
 2. The thermal management system of claim 1, wherein the heat exchanger defines a cooling channel, and wherein the first thermal transfer layer at least partially defines the cooling channel.
 3. The thermal management system of claim 1, wherein the thermal transfer element is sandwiched between the first thermal transfer layer and the second thermal transfer layer.
 4. The thermal management system of claim 1, further comprising a second thermal transfer element thermally coupled to the first thermal transfer layer and the second thermal transfer layer, wherein the first and second thermal transfer elements are associated with different thermal zones on the second thermal transfer layer.
 5. The thermal management system of claim 4, wherein the first and second thermal transfer elements are independently controllable.
 6. The thermal management system of claim 1, wherein each of the first and second thermal transfer layers comprise thermally conductive materials.
 7. The thermal management system of claim 1, wherein the second thermal transfer layer further includes a surface adapted for mounting a first electronic component and defining a first thermal zone.
 8. The thermal management system of claim 7, further comprising a second thermal transfer element, and wherein the second thermal transfer layer further includes a second area adapted for mounting a second electronic component and defining a second thermal zone, wherein the first thermal transfer element is adapted to transfer heat from the first thermal zone and the second thermal transfer element is adapted to transfer heat from the second thermal zone.
 9. The thermal management system of claim 8, wherein the first thermal zone and second thermal zone are adapted to generate different thermal energy levels.
 10. The thermal management system of claim 8, wherein the first thermal transfer element and the second thermal transfer element are independently controllable.
 11. The thermal management system of claim 1, wherein the thermal transfer element is controllable.
 12. A thermal management system, comprising: a first thermally conductive plate; a second thermally conductive plate parallel to and proximate the first thermally conductive plate, wherein the first thermally conductive plate and the second thermally conductive plate define a cooling fluid channel; a third thermally conductive plate parallel to and proximate the second thermally conductive plate; and a plurality of controllable thermoelectric coolers disposed between and coupled to the second thermally conductive plate and the third thermally conductive plate, wherein the thermoelectric coolers define multiple individually controllable thermal zones on the third thermally conductive plate.
 13. The thermal management system of claim 12, wherein the third thermally conductive plate comprises further includes an area adapted for mounting a first electronic component in at least one of the thermal zones.
 14. The thermal management system of claim 13, wherein said thermal zones may generate different thermal energy levels.
 15. A method for thermal management of electronic components, comprising: transferring thermal energy from a first electronics component to a heat transfer medium through a first thermal transfer element; transferring thermal energy from a second electronics component to the heat transfer medium through a second thermal transfer element; monitoring a first temperature associated with the first electronics component and a second temperature associated with the second electronics component; and independently adjusting the thermal transfer elements according to the monitored temperatures.
 16. The method for thermal management of claim 15, wherein the thermal transfer elements comprise thermoelectric coolers.
 17. The method for thermal management of claim 15, wherein the thermal transfer elements are disposed between and coupled to: a first thermally conductive layer coupled to the first and second electronic components; and a second thermally conductive layer exposed to the heat transfer medium.
 18. The method for thermal management of claim 15, wherein the heat transfer medium is a coolant.
 19. The method for thermal management of claim 15, further comprising transferring energy from a third electronics component to the heat transfer medium via a thermal transfer layer.
 20. The method for thermal management of claim 15, wherein transferring thermal energy from the first electronics component to the heat transfer medium comprises: transferring the thermal energy through a first thermally conductive layer to the first thermoelectric cooler; and transferring the thermal energy from the first thermoelectric cooler to the heat transfer medium through a second thermally conductive layer. 